Advertising guru Sir Martin Sorrell has called on Google and Facebook to address the "big issue" of failing confidence in the value of online advertising.
Sir Martin, founder and CEO of the world's biggest communications group, WPP, said it was not acceptable that advertisers were charged when only three seconds of an online video ad had been viewed, saying the measurement system was in need of "rapid overhaul".
He also highlighted the problem of online ad fraud, where false page impressions are generated by automated "bots" rather than human users.
Addressing the Media & Telecoms 2016 & Beyond conference in London, Sir Martin called on Google and Facebook to "come in under the tent" in reforming the way online advertising is measured. He accused Facebook of so far having "failed to grasp that nettle".
He revealed that WPP places $4 billion a year of advertising with Google, far more than the $2.5 billion spent with WPP's leading traditional media partner, Rupert Murdoch's 21st Century Fox and News Corp empire.
But he said that as advertising clients spent a high proportion of their budget online they were demanding more evidence that they were getting value.
"Online (spend) is approaching 30 per cent and procurement departments are starting to have a heavy look at spending online," he said. "There's a really big issue in the area of measurement.
Measurement of offline (traditional media) is far more stringent and the hurdle is much higher."
Sir Martin claimed that the current standard used in America was "if not broken, certainly is in need of a rapid overhaul". He said: "It is ludicrous to attribute a view to online on the basis of a three second view with 50 per cent of the sound being turned off."
Addressing the "duopoly" of the two Internet giants, he said: "They have to be prepared to share their data on a more sophisticated and integrated basis."
Responding to the criticisms, Eileen Naughton, managing director of Google in the UK and Ireland, said its "True View" system introduced on YouTube ensured that advertisers were not charged if a user switched an ad off after five seconds.
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